Star-Finders Astrolabes

Figure 1. Ahmad ibn Khalaf's Astrolabe, Baghdad (Iraq), 9-10th Century

“Astro” means “STAR” in Greek and “+Labe” derives its name from the Greek word “Labio” meaning “Taker” or “FINDER”. The astrolabe accordingly carries a very exciting name, literally meaning… a “STAR-FINDER”.[*]

Over a thousand-year period in Muslim Civilisation, epoch-making discoveries and contributions, such as the first record of a star system outside our own galaxy were made. Also astronomical instruments including celestial globes, armillary spheres, sextants and especially astrolabes were developed laying the foundation for modern-day astronomy. For example, according to Franz S Verlag, “Al-Farghani” wrote the first known substantial description of the astrolabe during the years 856-57 AD, the date of the star table, which was based on the Mumlahan Tables”. People from Muslim Civilisation continued to use and contribute extensively to this device that making astrolabes became an art.

Today the oldest astrolabes discovered are mostly from Muslim Civilisation and some of them sold in very high prices in auctions for their elegance and history. In this 1001 Inventions story let's explore the origins of astrolabes, its types, uses and much more.

Figure 2. "The Anatomy of an Astrolabe: One of the highlights of the Arts of the Islamic World auction in London is a magnificent 11th-century Umayyad brass astrolabe, signed by Muhammad ibn al-Saffar. Astrolabes are elaborate instruments designed to determine the solar or stellar hour at a specific location, allowing the user to make a number of astronomical or astrological observations. They were used by astronomers and navigators from classical antiquity to the Renaissance." (Source)

Table of Contents

  1. What is an astrolabe?
  2. Origins of Astrolabes
  3. Uses of Astrolabes
  4. Makers of Astrolabes 
  5. Types of Astrolabes
  6. Anatomy of Astrolabes
  7. How to make an Astrolabe
  8. Videos
  9. More Images

Figure 3.  Did you know? Background image of 1001 Inventions is actually from the surface of an Arabic Astrolobe

What is an astrolabe?

© 1001 Inventions -
Figure 4. From 1001 Inventions School of Scholars canvas ©1001inventions

The astrolabe, Professor David A. King defines, is a two-dimensional model of the universe that one can hold in one’s hands; its heavenly features include a star map and the ecliptic (both appearing in the rete), and its terrestrial features (engraved on various plates) serve specific latitudes or localities.

Some astrolabes were small, palm-size, and portable; others were huge. They were the astronomical analog computers of their time, solving problems relating to the position of celestial bodies, like the sun and stars, and time. In effect, they were the pocket watches of medieval astronomers. They could take altitude measurements of the sun; could tell the time during the day or night; or find the time of a celestial event such as sunrise, sunset, or culmination of a star.

From 1001 Inventions book: The Enduring Legacy of Muslim Civilization

The astrolabe is the most important astronomical calculating device before the invention of digital computers and the most important astronomical observational device before the invention of the telescope." Astrophysicist Harold Williams

Origins of Astrolabes

Figure 5. Aristotle teaching astronomy while using an astrolabe on a Arabic Manuscript (Image Source) - Turkish School's MS Ahmed III 3206 Aristotle teaching, illustration from 'Kitab Mukhtar al-Hikam wa-Mahasin al-Kilam' by Al-Mubashir (pen & ink and gouache on paper) located at the Topkapi Palace Museum, Istanbul, Turkey. (Source)

The astrolabe is thought to have originated in Ancient Greece. Though no examples have survived, Hipparchus, writing in around 150 BCE, is credited with discovering stereographic projection, the mathematical means of representing the 3D sky onto a 2D plate that is the basis of how the astrolabe works.

While the origin of the astrolabe may have been Greek, it is generally agreed that the design was then perfected in Muslim Civilisation – indeed the name Astrolabe comes from the Arabic (asturlab) which is a version of the Greek term astrolabos (star-holder/taker), but it is in the Golden Age of Muslim Civilisation that the astrolabe was highly developed and its uses widely multiplied. Introduced to Europe from Muslim Spain in the early 12th century, it was one of the major astronomical instruments until the modern times.

From 1001 Inventions book: The Enduring Legacy of Muslim Civilization

Astrolabes were used in classical times, possibly as early as the 2nd Century BC by Hipparchus in compiling his famous star catalog. They became especially popular in the Islamic world, and the oldest surviving example was made in the 9th Century AD by Ahmad ibn Khalaf. Astrolabes came to [Muslim Spain] in the 10th Century, and in the next century European manuscripts were being written describing how to use this instrument. In the early European universities, astrolabes were used to teach astronomical principles to students, and Geoffrey Chaucer wrote a treatise on their use in 1391. The Portuguese and subsequent explorers used the mariner's version on their travels during the Age of Exploration. However, by the 18th Century their use had been supplanted by newer, more accurate instruments and methods of calculation..." Nick Kanas, Star Maps: History, Artistry, and Cartography

Uses of Astrolabes

Figure 6.  Using an astrolabe for navigation, in Arabic manuscript by Iqbâl-nâma Nizâmî, Kâbul or Kandahar, 16th Century (Source)

"The astrolabe has many applications, such as working out heights of inaccessible objects, time of day and its position on earth. This is all done by the use of ingenius tables and figures that are imprinted on both sides of an astrolabe."*  It has many uses that astronomors in Muslim Civilisation recorded. For example 10th century famous astronomer Abdul-Rahman al-Sufi outlined over 1,000 uses of an astrolabe in his writings.

Using stereography, celestial spheres were enabled to be projected on to a 2D plane and form the important body of an astrolabe. These astrolabes were based on the ecliptic, and divided into 12 portions. Further, each portion was given a sign of the zodiac.

From Muslim HeritageUsing an Astrolabe by Emily Winterburn

The ability of Islamic civilization to perfect what it inherited, and to endow what it made with beauty, is nowhere better expressed than in the astrolabe." Oliver Hoare, Exhibition Catalogue, Riyadh, 1985

Makers of Astrolabes

Figure 7.  [Mariam]* Al-Ijliya al-Asturlabi (Source
(* First name Mariam was provided by the Syrian Archaeological Society, but remains to be corroborated)

As there are many uses, there are many makers of Astrolobes as some of them mentioned in this story.

The making of astrolabes, a branch of applied science of great status, was practiced by many include one woman from Aleppo (Syria), Mariam (*note above) “Al-Astrolabiya” Al-Ijliya (Al-'Ijliyah bint al-'Ijli al-Asturlabi), who followed her father's profession and was employed at the court of Sayf al-Dawlah (333 H/944 CE-357/967), one of the powerful Hamdanid rulers in northern Syria who guarded the frontier with the Byzantine empire in the tenth century CE.

Another name should be specially mentioned here "This remarkable astronomical instrument was made by the Muslim astronomer known as Nastūlus, who was active in Baghdad between 890 and 930. Its rediscovery brings our knowledge of the activities in that flourishing scientific centre a substantial step further" as Prof David A. King continues: 

Figure 8. (Right) This type of instrument was previously not known to exist. 
this instrument is important for the history of instrumentation for another reason: it partly resolves the question of the origin of the solar/
calendrical scales on Islamic instruments. Julio Samsó has favoured an Andalusī origin. Direct evidence from Late Antiquity of scales of this kind from either end of the Mediterranean is not available.
However, now we have an earlier example of them from Baghdad that is certainly without any Andalusī influence whatsoever.
David A. King, An Instrument of Mass Calculation made by Nastūlus in Baghdad ca. 900


From 1001 Inventions book: The Enduring Legacy of Muslim Civilization

Types of Astrolabes

Figure 9. Spanish stamp of Al-Zarqali with universal astrolabe (Source)

Most known ones called Universal Astrolobes. These were developed in Toledo in the 11th century, and it revolutionized star mapping. Two individuals, Ali ibn Khalaf al-Shajjar, an apothecary or herbalist, and Al-Zarqali, were important in this new development. The universal astrolabe was a major breakthrough because it could be used at any location. Ordinary astrolabes needed different latitude plates if they were moved, because  they were designed  for a certain place and were latitude dependent.

An important  aspect  of the universal  astrolabe was that its stereographic  projection used the vernal or autumnal equinox as the center of projection onto the plane of the solstitial colure.

There are, of course other types of astrolabe such as Nautical, Quadrant, Rojas Astrolabes, and Planispheric Astrolabe was one of the most popular one. Other one of the most interesting of them all was an astrolabe with geared calendar made by Muhammad b. Abi Bakr, Isfahan, 1221/2 as shown below. Muhammad ibn Abi Bakr al-Farisi (d.1278) was an Islamic astronomer born in Aden (Yemen). He is the author of al-Tuḥfa, which includes a treatise containing important information for the history of Islamic astronomy and its connection with the religion of Islam. This early Persian astrolabe with a geared calendar movement is the oldest geared machine in existence in a complete state. It illustrates an important stage in the development of the various complex astronomical machines from which the mechanical clock derives. Scholars from Muslim Civilisation learned of this design from a text by al-Bîrûnî, who explained how gearing might be used to show the revolutions of the sun and moon at their relative rates, and to demonstrate the changing phase of the moon. These phenomena were of fundamental importance in the lunar calendar used in Muslim Civilisation.

From 1001 Inventions book: The Enduring Legacy of Muslim Civilization


Figures 10-11  Abī Bakr al Ibarī's Astrolabe, 13th cent. is the oldest geared machine in existence in a complete state (Source)  

The astrolabe is an instrument maximum size, usable size, that we have and most people can see in museums etc. It is in the order of maybe 5-10 inches, they are all in that range. It is really a series of brass discs turning one on top of each other. You can manage to solve with all sorts of mathematical problems. The same Abdul Rahman al-Sufi, who worked on the stars, also wrote a book on the construction and use of an astrolabe. He gave us the list of 385 astronomical mathematical problems that could be solved with an astrolabe. Put briefly to our modern use and to our young people nowadays, it is nothing different, it is in change of function, it is just as efficient as your little pocket calculator that you use nowadays. Unfortunately nowadays most kids in schools use it to find the sum function and to multiply functions, which is what an astrolabe does. It is an ingenious application of mathematics onto a technology that allows you to solve mathematical problems."
Interview with Professor George Saliba

Anatomy of Astrolabes

Figure 12. Astronomers using an astrolabe from the Arabic illuminated manuscripts, a compendium of tales by al-Hariri of Basra, Iraq (1054-1122) illustrated by Yahya ibn Mahmud al-Wasiti: The Maqamat (Assemblies)

Astrolabes were the cutting edge of technology, used and developed by astronomers in Muslim Civilisation who were intrigued and fascinated by the heavens. It was through these hardworking scholars that the astrolabe made it into Europe, where modern astronomy was born. 

Figure 13. 
Diagram showing the parts of an astrolabe (Source)

Astrolabes, as an instruments for timekeeping, were eventually superseded by mechanical clocks and more advanced methods of calculation, but simplified astrolabes for stargazers are still made today.

- The tracings engraved on the astrolabe allow you to perform a variety of different calculations. For example, to tell the time at night, you line up a rule on the back of the astrolabe with a star to find its altitude. You rotate the rete until the star’s pointer sits on the correct altitude line on the plate, and read the time off the rim.

- Left, top, and right: The lines engraved on each plate are projections of the sphere of the sky overhead. Each plate covers a narrow range of latitudes (the pole’s altitude over the horizon).

- Center: The mater of the astrolabe is a hollow disc deep enough to hold several flat plates.

- Bottom: The rete has a circle (ecliptic) to track the sun’s path  across the sky, and pointers correspond to bright stars. Dagger-shaped pointers were characteristic of early astrolabes from Muslim Civilisation.

– the mater or base plate,

– the rete or top web-like plate which shows the fixed stars, the ecliptic (the zodiac constellations and part of the sky across which the Sun travels) and certain naked eye stars,

– the plates, each of which is made for a different latitude. Each plate has engraved on it a grid marking the zenith (point directly over head), the horizon and all the altitudes in between;

– the alidade or rule with sights used for making observations and reading off scales.

The rete and plates are designed to fit into the mater.

From 1001 Inventions book: The Enduring Legacy of Muslim Civilization

Figure 14. Ibrahim ibn Saîd's Astrolabe Toledo / Valencia (Spain), 11th cent. (Source
Figures 15. North African universal astrolabe
uses the ‘universal lamina' described by Al-Zarqali (Source)

How to make an Astrolabe

Figure 16.  "Treatise on the Astrolabe" 13th Century manuscript by Mahmud bin Muhammad al Mushi, Sivas, Turkey (Source

There are many articles and videos show how to make or use your own astrolabe. It was not so different in medieval times, there are manuscripts or books show how to use or construct various Astrolabes. For example Kitāb Fī Al-ālāt Al-falakīyah by François Charette "This volume contains the critical edition with English translation of a richly-illustrated Arabic treatise on the construction of over one hundred various astronomical instruments, many of which are otherwise unknown to specialists. It was composed by Najm al-D n al-Misr , a rather shadowy figure, in Cairo ca. 1330".*

Another example is "Treatise on the Astrolabe by a Seljuk-illustrated (Seljuq / Selcuk) Arabic manuscript in naskh script, copied by Mahmud bin Muhammad al Mushi, Sivas, Turkey, dated 1231. This is one of the earliest known extant copies of the treatise, originally by Abu Rayhan Muhammad Bin".*

Figure 17. A Seljuk's (Seljuq's / Selcuk's) Arabic Illustrated manuscript on the construction and use of the astrolabe, ink on paper Sivas and Kayseri, Anatolia (Turkey), 1231-1238 from the The al-Sabah Collection, Dar al-Athar al-lslamiyyah, Kuwait (LNS 67 MS) (Source)

Chaucer, famous British author of the Canterbury  Tales, also wrote a “Treatise on the Astrolabe” for his ten-year-old son, Lewis, in 1387.  We would like to finish our story with what he wrote to his son:

Little Lewis my son, I have . . . considered your anxious and special request to learn the Treatise of the Astrolabe . . . therefore have I given you an astrolabe for our horizon, constructed for the latitude of Oxford. And with this little treatise, I propose to teach you some conclusions pertaining to the same instrument. I say some conclusions, for three reasons. The first is this: you can be sure that all the conclusions that have been found, or possibly might be found in so noble an instrument as an astrolabe, are not known perfectly to any mortal man in this region, as I suppose."
Chaucer, Treatise on the Astrolabe

Figures 18-19. Kelmscott edition of Treatise, picturing Chaucer and his son Lewis, illustrated by William Morris (Source) and a illustration from the 1872 edition of  Chaucer's Treatise on the Astrolabe (Source)


More Images

Figure 20. Arabic Spherical astrolabe Signed by Musa 1480-81 (Source) Oxford, Museum of the History of Science, inv. 49687 Astrolabes show the heavenly vault on a flat surface. This is the only complete example of a spherical astrolabe to have come down to us. The rete records the positions of 19 fixed stars. (Source)

Figures21-22. The front and back of an Arabic Astrolabe in the Whipple Museum, Cambridge. This astrolabe is signed "Husain b. Ali" and dated 1309/10 AD. It is probably North African in origin, and is made of brass. It has four plates (for the front of the astrolabe, representing the projection of the celestial sphere and marked with lines for calculation), each for a specific latitude, and 21 stars marked on the rete (the star map, with pointers, fitting over the plate)


Figure 24. Calendar scales (round the outside edge) on an Arabic astrolabe in the Whipple Collection, Cambridge, a case of calendrical applications of Arabic astrolabes. Arabic astrolabes have calendar scales on them that enable the positions of the moon and the dates of the lunar calendar to be calculated easily.

Figures 25-26.  Front covers of In Synchrony with the Heavens by David A. King

image alt text 
Figures 27-28. Front covesr of The House of Wisdom: How the Arabs Transformed Western Civilization by Jonathan Lyons (Bloomsbury, 2009).

Figures 29-30. This astrolabe comprises five tympanums, of which four are for latitudes 0°/18°, 21°/24°, 30°/32°, and 34° (corresponding to the regions between Ethiopia and Syria). The inside of the mater carries the meridians and parallels. There is a rete: the zodiacal circle bears the names of the constellations in Latin. The back is inscribed with the names of the zodiac constellations in Latin and a shadow square. Dates from at least the fourteenth century, but may be older. Provenance: Medici collections.

Figure 31. From 1001 Inventions first exhibition, Manchester, UK, 2006

Figure 32.  (Image Source)

Figure 33. Part of the permanent exhibition Al-Andalus y la Ciencia on the Andalusian scientific heritage at the Fundación El legado Andalusí and el Parque de las Ciencias de Granada in Spain

Figure 34. From Albumasar's Introductorium in Astronomism, Venice, 1513 - Introduction à l'astronomie, contenant les huit livres divisés d'Abu Ma'shar Abalachus -  Abū Maʿshar, Jaʿfar ibn Muḥammad al-Balkhī, was an astrologer, astronomer, and philosopher, of the Abbasid court in Baghdad (Source)

Figures 35-36. Unknown image - supposedly illustraion of a Moorish (Andalusian) astronomer using an astrolobe (Source) (Source)

Figures 37-38. Arabic astrolabes of the ninth and tenth centuries with Armenian inscriptions [ History of the Armenian astronomy B. E. Thoumanian, Yerevan, 1964] (Source)

Figures 39-40. Depiction and description of an astrolabe after al-Biruni, 18th century. Illustration to: Kitab al-tafhim li-avail sinaat al– tanjum (introduction to the basics of astrology) (Source) (Source)

Figure 41. "Drawing, by Matthew Paris, from the Liber Experimentarius of Bernardus Silvestris. Euclid holding a sphaera and looking through a dioptra. Beside him sits Hermann of Carinthia, a mediaeval translator of Arabic works on astronomy, holding an astrolabe. Dated 13th Century" (Source)


Figures.42-43. Beginning of 12th Century Muhammad ibn Abi'l Qasim ibn Bakran's Astrolabe (Source)

Figure 44. "An early seventeenth century margin drawing from the folio in Jahāngīr's Album showing an astrologer surrounded by his equipment—an astrolabe, zodiac tables and an hour glass (courtesy: Werner Forman Archive/Naprestek Museum, Prague). " (Source)

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